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Date: Wed, 02 Mar 2011 08:57:26 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [RFC][PATCH 0/2] Allow cache settings for block
	devices to be changed at runtime.
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: qemu-devel <qemu-devel@nongnu.org>, Ananth Narayan <ananth@linux.vnet.ibm.com>, Christoph Hellwig <hch@lst.de>, Prerna Saxena <prerna@linux.vnet.ibm.com>, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Am 01.03.2011 20:13, schrieb Anthony Liguori:
> On 03/01/2011 07:50 AM, Christoph Hellwig wrote:
>> On Tue, Mar 01, 2011 at 12:48:34PM +0000, Stefan Hajnoczi wrote:
>>    
>>> On Tue, Mar 01, 2011 at 01:42:54PM +0100, Christoph Hellwig wrote:
>>>      
>>>> I have patches to do that, and to allow changing O_DIRECT via a monitor
>>>> command, but to toggle O_SYNC via fcntl I first need to get a kernel
>>>> patch in as that's currently not allowed to be changed at runtime.
>>>>        
>>> Great it sounds like you have already implemented the two cases (guest wce and
>>> host O_DIRECT) that we're talking about.
>>>      
>> At least in theory.  And for Linux I can add setting/clearing of O_SYNC
>> via fcntl easily, but what do we do for other hosts?
> 
> To start with, we can just fail the command at the QMP level.

O_SYNC isn't toggled from QMP but from the guest.

Kevin